Testing golang http2 client and server

http2_test.go

package http2_test

import (
	"crypto/tls"
	"crypto/x509"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"golang.org/x/net/http2"
)

func getMux(t *testing.T) *http.ServeMux {
	// define our http handler
	mux := http.NewServeMux()
	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		t.Logf("received request: %+v", r)
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("foo bar!"))
	})

	return mux
}

func TestMakeHTTPConnection(t *testing.T) {
	// start an http1.1 server
	srv := httptest.NewUnstartedServer(getMux(t))
	srv.EnableHTTP2 = false
	srv.Start()
	defer srv.Close()

	// create a http1.1 client
	transport := http.DefaultTransport.(*http.Transport).Clone()
	httpClient := http.DefaultClient
	httpClient.Transport = transport

	// perform http1 request
	_, err := httpClient.Get(srv.URL)
	if err != nil {
		t.Errorf("error while performing http1 request: %s", err.Error())
	}
}

func TestMakeHTTP2Connection(t *testing.T) {
	// start an http2 server
	srv := httptest.NewUnstartedServer(getMux(t))
	srv.EnableHTTP2 = true
	srv.StartTLS()
	defer srv.Close()

	transport := http.DefaultTransport.(*http.Transport).Clone()
	
	// trust the servers tls cert
	certpool := x509.NewCertPool()
	certpool.AddCert(srv.Certificate())
	tlsconf := &tls.Config{RootCAs: certpool}
	transport.TLSClientConfig = tlsconf
	
	h2Transport, err := http2.ConfigureTransports(transport)
	if err != nil {
		t.Errorf("error while configuring http2 transport: %s", err.Error())
		return
	}

	h2Transport.ReadIdleTimeout = time.Second * 1 // ping is performed at N whenever no frame was received in the meantime
	h2Transport.PingTimeout = time.Second * 3     // after what time a ping is considered timed out

	
	http2Client := http.DefaultClient
	http2Client.Transport = transport

	// perform http2 request
	_, err = http2Client.Get(srv.URL)
	if err != nil {
		t.Errorf("error while performing http2 request: %s", err.Error())
	}
}

Please make sure that for a self signed server certificate, like in this example, you have to configure the TLSClientConfig before you call http2.ConfigureTransports(...) and thus upgrading your http1.1 connection to http2. Otherwise you will receive a connection pool error but it really should be a cert error from golang's side. This is rather unlucky.